DESCRIPTION: (Applicant's Abstract) Vision disorders are the leading cause of handicapping conditions in childhood. The Preschool Children's Vision Screening Study Group (PCVSSG) proposes a randomized clinical trial to identify a screening test or combination of screening tests, which can be administered primarily by lay people, that have high sensitivity and specificity in identifying children in need of further evaluation for amblyopia, strabismus and significant refractive error that are prevalent significant vision disorders of early childhood. This planning grant proposal is a request for the financial support of the development and refinement of procedures for a multicenter, randomized clinical trial of a battery of screening tests to identify three-year-old children in need of further vision care for amblyopia, strabismus and significant refractive error. In the proposed study the PCVSSG will conduct pilot projects to validate a logMar pediatric visual acuity test planned for use in the clinical trial, to compile representative photographs that will be used in the interpretation of photorefraction test results, and to demonstrate the feasibility of conducting all the major procedures to be used on three-year-old children in the clinical trial. Also, during the planning period standardized protocols will be developed for each of the screening and diagnostic procedures, training materials will be developed for the screeners, and a manual of procedures for the clinical trial will be written.